Seminar Series

'MEG correlates of recognition'

In this talk I will present MEG data obtained during a recognition memory study using verbal materials. The data were analysed using a novel method known as synthetic aperture magnetometry (SAM), which provides spatial and temporal information associated with power changes in the frequency spectrum of the magnetic field. Results revealed a differential distribution of event-related synchronisations and de-synchronisations for correctly recognised old items and correctly rejected new items in the analysed frequency bands (1-3 Hz, 4-8 Hz, and 9-12 Hz). Based on the SAM results, source waveforms were calculated for a number of voxels with significant power changes in the different frequency bands. These source waveforms allowed a more fine-grained analysis of differences in the power changes associated with the correct discrimination between old and new items. Results of both types of analyses suggest that the determination of ‘oldness’ and ‘newness’ of items in the context of a recognition memory task is dependent on a number of processes which are dissociable neuronally in time, space and frequency range.